Piles or columns supporting a vertical load can deteriorate over time, particularly in marine environments. Tides, water currents, sedimentary sand abrasion, floating debris, marine insects, wide temperature gradients, and weathering all contribute to deterioration of the column while the column bears a continuous load. Bridges and docks are examples of architectural structures that are supported by columns in marine environments. Columns can be made of concrete, steel, or wood, for example. Deteriorated columns, or more generally, weight-bearing members, are typically repaired in place because of the high cost to replace each column that requires repair. Moreover, even as our infrastructure ages, there is inevitably little public funding available to replace or build anew; rather, existing structures are often necessarily repaired and strengthened to save cost. Column restoration is a dangerous and arduous process because the columns often extend several feet under water and are difficult to access. Further, rehabilitating marine columns often must be done quickly because much of the repair takes place while under water and under tidal influence. Occasionally, the repair site must be “de-watered” to prevent water from interfering with the column restoration.
Shells or jackets have been introduced to protect columns from further deterioration. Shells are designed to surround the column above and below the area of deterioration. A shell is placed around the column and then grout or an epoxy can be poured or pumped into the space between the shell and the column. The shell provides a permanent form that protects the column from further deterioration while retaining the epoxy or grout that fills the voids in the column. The epoxy or grout also prevents water or environmental deteriorants from contacting the damaged portion, or any other covered portion, of the column. However, little structural capacity is added to the column by the shell and epoxy or grout combination.
Shells that can both increase the structural capacity of columns and at the same time protect the columns from deterioration are desirable in many situations. For example, bridges that were built several decades ago may be supported by columns that were designed to support smaller loads and comply with less stringent design standards than are required by today's codes and regulations. A bridge built in 1950, for example, may have been designed and built to support trucks up to 40,000 lbs, and would need to be enhanced to support increased traffic and the heavier trucks of today (e.g., 70,000 lbs), as well as to comply with more stringent structural codes and regulations. Moreover, the columns supporting such a bridge may have deteriorated over time such that the weight-bearing capacity of the bridge has decreased. In some columns, such as wood or timber columns, the deterioration may have taken place inside the column and may be difficult to see or estimate the degradation of structural capacity.
Conventional shells are limited in ability to substantially increase the structural capacity of weight-bearing members because they are limited to the strength of the shells themselves, or more specifically, the connection at the seam in the shell. Examples of conventional shells are disclosed in U.S. Pat. No. 4,019,301 to Fox. Such conventional shells lack reinforcement and a continuity connection system that provides continuity for both the reinforcement and the shell, which continuity connection systems substantially increase the confinement strength of the system. Conventional shells may be strengthened in some manner on the exterior of the shell, but such additional support is subject to the same tides, water currents, sedimentary or sand abrasion, floating debris, marine insects, wide temperature gradients, and weathering that caused deterioration of the column in the first place.
Conventional shells do not have structural enhancements built within or into the shell, such as a reinforcement layer and a continuity connection system, that substantially enhance the structural capacity of the column. The present invention has been found to substantially increase the structural capacity and solve many problems inherent in conventional shells and column-restorative procedures, and may prove helpful in rehabilitating and strengthening an aging infrastructure.